Abstract
A cDNA encoding a ubiquitin-conjugating enzyme designated UbcP4 in fission yeast was isolated. Disruption of its genomic gene revealed that it was essential for cell viability. In vivo depletion of the UbcP4 protein demonstrated that it was necessary for cell cycle progression at two phases, G2/M and metaphase/anaphase transitions. The G2 arrest of UbcP4-depleted cells was dependent upon chk1, which mediates checkpoint pathway. UbcP4-depleted cells arrested at metaphase had condensed chromosomes but were defective in separation. However, septum formation and cytokinesis were not restrained during the metaphase arrest. Overexpression of UbcP4 specifically rescued the growth defect of cut9ts cells at a restrictive temperature. cut9 encodes a component of the anaphase-promoting complex (APC) which is required for chromosome segregation at anaphase and moreover is defined as cyclin-specific ubiquitin ligase. Cdc13, a mitotic cyclin in fission yeast, was accumulated in the UbcP4-depleted cells. These results strongly suggested that UbcP4 is a ubiquitin-conjugating enzyme working in conjunction with APC and mediates the ubiquitin pathway for degradation of "sister chromatid holding protein(s)" at the onset of anaphase and possibly of mitotic cyclin at the exit of mitosis.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Sequence
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Anaphase* / genetics
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Apc6 Subunit, Anaphase-Promoting Complex-Cyclosome
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Carrier Proteins / genetics
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Carrier Proteins / metabolism
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Checkpoint Kinase 1
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Cyclin B
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Cyclins / genetics
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Cyclins / metabolism
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DNA, Complementary / chemistry
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DNA, Complementary / isolation & purification
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DNA, Fungal / chemistry
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Fungal Proteins / genetics
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Fungal Proteins / metabolism
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G2 Phase
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Ligases / genetics
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Ligases / metabolism*
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Macromolecular Substances
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Mitosis* / genetics
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Molecular Sequence Data
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Mutagenesis
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Nuclear Proteins*
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Protein Kinases / metabolism
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Restriction Mapping
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Schizosaccharomyces / cytology
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Schizosaccharomyces / enzymology*
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Schizosaccharomyces / genetics
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Schizosaccharomyces pombe Proteins*
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Temperature
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Ubiquitin-Conjugating Enzymes*
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Ubiquitins / metabolism
Substances
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Apc6 Subunit, Anaphase-Promoting Complex-Cyclosome
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CUT9 protein, S pombe
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Carrier Proteins
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Cyclin B
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Cyclins
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DNA, Complementary
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DNA, Fungal
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Fungal Proteins
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Macromolecular Substances
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Nuclear Proteins
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Schizosaccharomyces pombe Proteins
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Ubiquitins
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ubiquitin carrier proteins
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Ubiquitin-Conjugating Enzymes
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ubc11 protein, S pombe
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Protein Kinases
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histone H1 kinase
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Checkpoint Kinase 1
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Chk1 protein, S pombe
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Ligases
Associated data
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GENBANK/D85544
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GENBANK/D85545